notification support

app.py

@@ -58,7 +58,7 @@ def get_version() -> str:
 @app.context_processor
 def inject_version() -> Dict[str, str]:
     """Injects the version into all templates."""
-    return dict(version=get_version())
+    return dict(version=get_version(), config=app.config, session=session)
 
 @app.before_request
 def make_session_permanent() -> None:

static/service-worker.js

@@ -21,6 +21,19 @@ self.addEventListener('install', function(event) {
   );
 });
 
+self.addEventListener('push', function(event) {
+  const data = event.data.json();
+  const options = {
+    body: data.body,
+    icon: '/static/web-app-manifest-192x192.png',
+    badge: '/static/favicon-96x96.png'
+  };
+
+  event.waitUntil(
+    self.registration.showNotification(data.title, options)
+  );
+});
+
 self.addEventListener('fetch', function(event) {
   event.respondWith(
     caches.match(event.request)

templates/base.html

@@ -54,8 +54,62 @@
     <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>
     {% block scripts %}{% endblock %}
     <script>
-        if ('serviceWorker' in navigator) {
+        if ('serviceWorker' in navigator && 'PushManager' in window) {
-            navigator.serviceWorker.register('{{ url_for("static", filename="service-worker.js") }}')
+            window.addEventListener('load', function() {
+                navigator.serviceWorker.register('{{ url_for("static", filename="service-worker.js") }}').then(function(registration) {
+                    console.log('ServiceWorker registration successful with scope: ', registration.scope);
+                    askPermission(registration);
+                }, function(err) {
+                    console.log('ServiceWorker registration failed: ', err);
+                });
+            });
+        }
+
+        function askPermission(registration) {
+            Notification.requestPermission().then(function(result) {
+                if (result === 'granted') {
+                    subscribeUser(registration);
+                }
+            });
+        }
+
+        function subscribeUser(registration) {
+            const applicationServerKey = urlB64ToUint8Array('{{ config.VAPID_PUBLIC_KEY }}');
+            registration.pushManager.subscribe({
+                userVisibleOnly: true,
+                applicationServerKey: applicationServerKey
+            }).then(function(subscription) {
+                console.log('User is subscribed.');
+                saveSubscription(subscription);
+            }).catch(function(err) {
+                console.log('Failed to subscribe the user: ', err);
+            });
+        }
+
+        function saveSubscription(subscription) {
+            fetch('/save-subscription', {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'Authorization': 'Basic {{ session.auth_credentials }}'
+                },
+                body: JSON.stringify(subscription)
+            });
+        }
+
+        function urlB64ToUint8Array(base64String) {
+            const padding = '='.repeat((4 - base64String.length % 4) % 4);
+            const base64 = (base64String + padding)
+                .replace(/\-/g, '+')
+                .replace(/_/g, '/');
+
+            const rawData = window.atob(base64);
+            const outputArray = new Uint8Array(rawData.length);
+
+            for (let i = 0; i < rawData.length; ++i) {
+                outputArray[i] = rawData.charCodeAt(i);
+            }
+            return outputArray;
         }
     </script>
 </body>